<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
</body>
</html>
<script>
    // string 首字母大写  
    const capitalize = (s) => {
        if (typeof s !== "string") return "";
        return s.charAt(0).toUpperCase() + s.slice(1);
    }
    console.log(capitalize("cat")); // Cat
    // 截取字符串 
    const truncate = (text, num = 10) => {
        if (text.length > num) {
            return `${text.substring(0, num - 3)}...`
        }
        return text;
    }
    console.log(truncate("this is some long string to be truncated"));   // this is ...
</script>